Magnetic wedge.



C. ROBINSON.

MAGNETIO WEDGE.

APPLIOATION FILED Jule, 1907.

917,138. Patented Apr. 6, 1909.

KIWI/$ 55555 NYE/V705 k W' ZZZ YI/IZAY 5/75/51 ATTY.

Norms I'EIERs. INC LiYHuH WASPHNOH-N, D c

UNITED STATES PATENT OFFICE.-

CONWAY ROBINSON, OE'SCHENECTADY, NEW YORK, ASSIGNOR; TO GENERALELECTRIC" COMPANY, A CORPORATION OF NEW; YORK.

maennrrc WEDGE;

m5. 9 mice.

. Specification of Letters Patent.

To all whom it'may concern:

Be it known that I, CONWAY ROBINSON, a

citizen of the United States, residing at- Schenectady, county ofSchenectady, State of New. York, have invented certain new and "usefulImprovements in Magnetic Wedges, of? which the following is aspecification.

My invention relates to dynamo-electric machines and particularly to wede devices for retaining conductors in: slots ormed in the corestructures, and it has for its object to improve such devices.

In the stators of induction. motors, par.-

ti'cularly, it-is of ad'vant'ageto have the surface 'of the corepresent, as nearly as possible an unbroken area of magnetic material toeffect a uniform'di'stribution of the flux and decrease'the reluctanceof the air gap.

.It is also desirable in this and other types of dynamo-electricmachines to bring the condiictors as near the surfaceas possible inorder-to reduce the length of the magnetic circuits toa minimum. Theretaining wedge should therefore be preferably formed in part, at least,of magnetic material, and shouldbe mechanically strong in order that itmay be made as thin as possible and thereby permit theconductor-receivingslot to be made only slightly deeper than the depthof the conductors. It is also, of course,.necessary to divide themagnetic material 'of the wedge or retaining device in such a waythat noeddy currents are set up therein.-

M'y invention therefore consists in a novel construction and arrangementof parts constituting a wedge having the above and.

other-desirable characteristics. The various features of novelty w1ll bepointed out withparticularity in the appended claims; but for a fullunderstanding of" he invention and of its various objects and.advantages reference may be had to the following detailed descriptiontaken in connection withthe accompanying drawing which shows a preferredembodiment.

Insaid drawing, Figure 1 shows a portion of" a dynamo-electric machinehaving the improved retaining device applied to the armature or rotorthereof; Fig. 2 1s a per- Vsipective view of a section of a retainingvice; Fig. 3 is an enlarged view showing in'cross-section a set ofconductors arranged in a slot with the retaining dev ce in position; andFig. 4 shows a portion of an 1ndu ction motor having the retainingdevices applied tothe stator.

Reference being had to the drawin A.

indicates the improved" wedge as a w ole.

It is madein such form. that when in positionit partially bridgestheslot with mag: netic material'so as to form a pole tip or tips adjacentthe slot. It may conveniently be made in the form of a pair; of magneticstrips land 2, secured or cemented to a back ing 3', which is preferablymade of. fiber on some other tough material, adding to the strength ofthe wedge and at the same time providing a. certain elasticity whereby.the

wedge may readily adjust itself to the slot into which it is driven. Themembers 1 h and 2'are preferably of subdivided magnetic material so asto avoid eddy losses. "For thls purpose iron-wool, or iron filings, heldtogether by some suitable electrically nonrthe transverse direction. Themember 3 may conveniently be made of'wood pul'p, asbest-os or some otherfiber also held together by a suitable binder. I have found. thatsodiuni silicate may be used to advantage as the binder for the magneticmaterial, and" gelatin chromateas a binder for the fiber; Theseparticular compositions need not necessarily be used, however.

The member 3 preferably takes theshape of a slightly curved slab havinga thin, and preferably tapered, central rib 4 projecting from one sidethereof. When made of some fibrous material held together by a suitablebinder, it is preferably formedby'placing the plastic material insuit-able dies upon which suflicient pressure is exerted to squeeze thewhole into a tough mass. This is then dried and placed in another die ormold having the shape of the completed wedge. The material of themagnetic portions is then introduced into this latter die or mold andpressure is again exerted until the magnetic portions together with, theslab of fibrous material are pressed and cemented into a hard. compactform. The whole is then dried, and, if desired,provid'ed with a coatingof'varnish. The resulting wedge is exceedingly stifl and strong.

The rib on the member 3 is preferably of such lengththat its outer edgeissubstantially flush With the upper surface of the magnetic portions 1and 2 and the combined Widths of this rib and the magnetic portions(which is equal to the Width or". the slot into which the Wedge is to bedriven), is somewhat less than the Width of the body portion of themember 3, \vherebybeads 5 and 6 are formed at the sides of the wedge bythe projecting portions of the fiber backing.

T he manner of using the WGClQG is shown in Fig. 3, wherein 7 indicatesa fragment of core having a coil-receiving slot 8. 9 and 10 are twocoils arranged one above the other 'in the slot. The slotmayconveniently be made rectangular in form with a pair of under-cutgrooves 11 and 12 on opposite sides thereof at points adjacent the topof the uppermost coil. These grooves are adapted to receive the beads 5and 6 of the Wedge. The parts are so proportioned that the outer surfaceof the Wedge is flush With the outer surface of the core member.

It will be seen that the magnetic portions 1 'the Wedge to the other,and causes the flux to pass in the proper direction from each pole-tipdown into the core body By making the bottom of the wedge curved, asshown, whereby it tits the upper surface of the conductor 9, an addeddepth is given to the Wedge Without necessitating an increase inthedepth of the slot as a- Whole. I v

Referring to Fig. 1, 13 indicates the field magnet, 0r stator, of adynamo-electric machine, and 14 the armature, or rotor, which.

has a core 7 provided With slots8 forthe conductors 9 and 10. Eachsetofconductors, it- Will be seen, is held in place by one of the Wedgedevices. p I

In Fig. 4.- I have shown an induction motor comprising stator and rotorn'ieinbers l5- and 16, respectively; the retaining devicesjit being usedto hold the coils 17 and'18 in place.

In direct current machines, it is not necessary that the Wedges bemagnetic'and in stead of iron or steel wool, copper WOOl may be employedto advantage.

While I have described in detail a preferred form of my invention, 1 donot desire to be limited to the particular arrangement, of parts shownsince in its broader aspects my invention contemplates other.

constructions emlwdying the essential tea turcs a1 defined in the appendd claims.

What 1 claim as new and desire to secure by Letters atom 01' the llnitedStates, is,-

1. As an article of manufacture, a slotclosing device consisting of abar composed of" magnetic material whose continuity is inicrrnpted byportions of electrically nonconducting: material and a central layer ol'non-magnetic material dividing said bar into two portions, said bar andsaid central layer being cemented together.

2. As an article of manufacture, a slot closing device consisting of abar composed cf linely divided portions of magnetic material heldtogether by a binder of electriially non-conducting material, said barhaving a central portion of non-magnetic material, said bar and saidcentral portion being cemented together. As an article ofnninufacture,a'slot closingdevice consisting of strips composed of finely dividedmagnetic material held together by electrically non-conducting bindmgmaterial, together with an interposed strip of non-magnetic material,said strips being cemented together.

i. As an article of manufacture, a slotclosing device consisting of afiber backing having a projecting rib on one side and strips composed offinely divided portions of magnetic material held togetherby a binder ofelectrically non-conducting material, arranged on'opposite sides of saidrib, said backing and said strips being ce merited together.

5. As an article of manufacture, a slotclosing-device consisting 01"- afiber backing having a central rib on one side and a fillingoffinely-divided magnetic material and electricallyv non-conductingbinding mate rial on opposite sides of the rib, said fiber backing andsaid filling being cemented together.

6.';-\.s an article of manufacture, a slotclosing device consisting of abar of mag netic material divided into two halves by a strip ofnon-magnetic material and backed by a layer of non-magneticmaterialwhich projects beyond the sides of the bar to form tips being separatedby and cemented to a strip of nonmagnetic material. 7

8. Thecombination with a dynamo-electric machine having coil-retainingslots with grooves in the sides thereof andcoils in said slots, ofslot-closing devices consist- ,ing each of a strip of non-magneticmaterial -tr1c machlne having coll retaining slots, of

concaved on its under side to fit the top of the coils and havingprojecting heads at the edges adjacent the concaved side fitting saidgrooves and portions of metal Wool cemented -to said strip.

9. As an-article of manufacture, -a slotclosing device consisting of abar composed of metal wool held to ether by an electricallynon-conducting binder.

10. As an article of manufacture, a slotvices each in the form of a pairof pole tips composed of magnetic-woohsaid tips being separated by andcemented to a strip of non-ma et'ic material.

- 12. T e combination with a dynamo-elecslot closing devices eachconsisting of a bar of metal Wool cemented to a strip of .nonmagnetic1nateria1.

1E The combination With a dynamo-electric machine having coil retainingslots, of slot closing devices each consisting of a fiber backing,having a projecting rib on'one side and strips of'm'agnetic woolcemented to opposite sides of said rib.

14.-As an article of manufacture, a slot closing device consisting of apair of pole tips composed of magnetic Wool separated by and cemented-toa strip of non-magnetic material.

In WVitIlGSS whereof, I have hereunto set my hand this 7th day ofJanuary, 1907.

CONWAY ROBINSON.

Witnesses:

BENJAMIN B. HULL, HELEN Onronn.

